.
Re: Regarding HEADSPACE, what is the
Well, I can tell you that .014 clearance makes brass break on the 3rd reload. LC, Win, Fed. Nothing survives that kind of stretching long.
My next loads have about .0005 to .001 clearance.
ETA: I was thinking last night about asking what was the *minimum" bump-back anyone was using...
Well, I can tell you that .014 clearance makes brass break on the 3rd reload. LC, Win, Fed. Nothing survives that kind of stretching long.
My next loads have about .0005 to .001 clearance.
ETA: I was thinking last night about asking what was the *minimum" bump-back anyone was using...
Re: Regarding HEADSPACE, what is the
.
.
Re: Regarding HEADSPACE, what is the
I bump my 6XC around .002-.003. I have loaded some of my brass up to 6 times and still no failures or loose primer pockets. I have a Redding body die that will bump .008 if I screw it all the way down to cam over but do not use it this way.
I bump my 6XC around .002-.003. I have loaded some of my brass up to 6 times and still no failures or loose primer pockets. I have a Redding body die that will bump .008 if I screw it all the way down to cam over but do not use it this way.
Re: Regarding HEADSPACE, what is the
This is the easiest way to measure your headspace clearance. I recommend our <span style="font-weight: bold">Digital Headspace Gauge</span>. Just zero the gauge on a fireformed case, then measure your handloads. The gauge displays the exact clearance that YOUR handloads will have in YOUR particular chamber. This makes it easy to set your die height perfectly.
Check it out on our website:
- Innovative
This is the easiest way to measure your headspace clearance. I recommend our <span style="font-weight: bold">Digital Headspace Gauge</span>. Just zero the gauge on a fireformed case, then measure your handloads. The gauge displays the exact clearance that YOUR handloads will have in YOUR particular chamber. This makes it easy to set your die height perfectly.
Check it out on our website:
- Innovative
Re: Regarding HEADSPACE, what is the
You don't need a gauge at all for a bolt action, remove the firing pin, remove the ejector, and resize the case until you feel a slight felt resistance when closing the bolt, what your magic number is does'nt matter, this will ensure the brass fits your chamber perfectly.
You don't need a gauge at all for a bolt action, remove the firing pin, remove the ejector, and resize the case until you feel a slight felt resistance when closing the bolt, what your magic number is does'nt matter, this will ensure the brass fits your chamber perfectly.
Re: Regarding HEADSPACE, what is the
If you're loading brass that has a low shoulder, as is common on belted magnums, the solution is to form a false shoulder on the neck before fire-forming (first firing). Then you will have no issues with head-spacing, regardless of caliber. This solution is recommended where head-spacing issues are recognized.
If you're loading brass that has a low shoulder, as is common on belted magnums, the solution is to form a false shoulder on the neck before fire-forming (first firing). Then you will have no issues with head-spacing, regardless of caliber. This solution is recommended where head-spacing issues are recognized.
Re: Regarding HEADSPACE, what is the
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 308sako</div><div class="ubbcode-body">Maximum permissible amount that would not cause detrimental results?
Not what is ideal, but rather what becomes the threshold of dangerous.
.003", .005", .008" etc. </div></div>
This is a malformed question.
One CAN use a chamber and a cartrige of smaller dimensions to fire form the case from one caliber to aother. In this application, the headspace only has to be such that the firing pin ignites the primer. The powder will take care of resizing the brass. With the low-ish pressures used to fire form, this is a completely safe activity.
For a case that will only see the inside of a chamber once, you can get away with all sorts of big sloppy dimensions. You may even see/hear stories about 308 cases run through a machine gun where the cases are really hard to resize back into tight bolt gun chambers. If the brass is only going to be used once, you may be able to get away with 0.010 (or more) as long as the firing pin can reach the primer and ignite same.
So we come back to the wear aspect. Brass wears by being stretched by firing, and then resized by the resizing die. This effects 3 main areas, the neck, the sholder, and the case just above the web. A bushing die minimizes the work hardening of the case neck, annealing extends the life of the neck. Properly used, these methods can allow the necks to last as long as 50 reload cycles (and more).
This basically leave the discussion with the sholder (position) and the case strech). For brass that is only shot in one gun, minimal resizing is in order, and the cases will attain the correct external dimensions from being fired. after a hand-full of reload cycles, you may have to bump the sholder back 0.002 and get another hand-full of cycles befor doign it again. These cases will have a very long life.
For brass that has to be capable of firing in any correctly headspaced SAAMI chamber, you are not so lucky, and should stick to FL sizing. You will not get the same case life, and this is simply part of the "utility" of a standard (as opposed to an optimized) load.
Finally notice that how stif the load is changes how the cases react. Peak Chamber pressures under 50K PSI can result in cases lasting as long as the necks do. Chamber pressures of 58K PSI still achieve cases that can last 50-ish reload cycles. Venturnign beyond 58K PSI will drop case life rapidly from "quite long" to "a few" in rather short order. Ejextor wipe, punched primers, primer pockets lostening up are sure signs of chamber pressure.
So, with a nice mild load, a case used only once can stand more headspace than most firing pins provide capability to set off the primer it holds.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 308sako</div><div class="ubbcode-body">Maximum permissible amount that would not cause detrimental results?
Not what is ideal, but rather what becomes the threshold of dangerous.
.003", .005", .008" etc. </div></div>
This is a malformed question.
One CAN use a chamber and a cartrige of smaller dimensions to fire form the case from one caliber to aother. In this application, the headspace only has to be such that the firing pin ignites the primer. The powder will take care of resizing the brass. With the low-ish pressures used to fire form, this is a completely safe activity.
For a case that will only see the inside of a chamber once, you can get away with all sorts of big sloppy dimensions. You may even see/hear stories about 308 cases run through a machine gun where the cases are really hard to resize back into tight bolt gun chambers. If the brass is only going to be used once, you may be able to get away with 0.010 (or more) as long as the firing pin can reach the primer and ignite same.
So we come back to the wear aspect. Brass wears by being stretched by firing, and then resized by the resizing die. This effects 3 main areas, the neck, the sholder, and the case just above the web. A bushing die minimizes the work hardening of the case neck, annealing extends the life of the neck. Properly used, these methods can allow the necks to last as long as 50 reload cycles (and more).
This basically leave the discussion with the sholder (position) and the case strech). For brass that is only shot in one gun, minimal resizing is in order, and the cases will attain the correct external dimensions from being fired. after a hand-full of reload cycles, you may have to bump the sholder back 0.002 and get another hand-full of cycles befor doign it again. These cases will have a very long life.
For brass that has to be capable of firing in any correctly headspaced SAAMI chamber, you are not so lucky, and should stick to FL sizing. You will not get the same case life, and this is simply part of the "utility" of a standard (as opposed to an optimized) load.
Finally notice that how stif the load is changes how the cases react. Peak Chamber pressures under 50K PSI can result in cases lasting as long as the necks do. Chamber pressures of 58K PSI still achieve cases that can last 50-ish reload cycles. Venturnign beyond 58K PSI will drop case life rapidly from "quite long" to "a few" in rather short order. Ejextor wipe, punched primers, primer pockets lostening up are sure signs of chamber pressure.
So, with a nice mild load, a case used only once can stand more headspace than most firing pins provide capability to set off the primer it holds.
Re: Regarding HEADSPACE, what is the
.
.
Re: Regarding HEADSPACE, what is the
With Lapua brass and 155 Scenars at 2800 fps, you are so far inside the safety lmits, I suspect you are down closer to 50K PSI--and should expect brass life approximately=infinity, neck life will depend on how you perform the resizing operations. Neck sizing in 2 steps from approx 0.344 to 0.335 (Lapua) should allow you to get 20-ish reload cycles without annealing, with annealing double to tripple that.
I run weaker Winchester cases and load them up to 47.8 gr Varget* with 155 scenars leaving at 2925-2950 fps. I am currently running a non-annealing experiment usign this load. I have one set (of 50) cases that is on its 24th reload cycle without annealing.
(*) with Lapua cases you should stop near 47.5 gr which will have the same MV as 47.8 gr Varget does in Win cases. THis is from the change in case volume between L and W.
But back to the originating question: You want the headspace to be just enough that the cartrige CAN rattle around in the chamber--and by being able to do so, the case self centers and shoot accurately. Thus, you need about 0.001 radially, and about 0.001-0.002 longitudinally with 0.002-0.003 radially in the neck/throat. Any more sizing than this wears the case near the web as the case reexpands to fit the chamber durring firing and the front of the case is gripping the cham ber near the neck. The bolt is driven back (a thou or so) giving the case room to grow longitudinally. Minimizing the body sizing increases the life of the brass--and may come with a tiny amount of accuracy loss.
So, we reach a quandrary, shoot that 0.05" better and win the match, or shoot that triffling worse and have brass live a long time reducing costs. Both are good strategies--depending on the intended outcome.
With Lapua brass and 155 Scenars at 2800 fps, you are so far inside the safety lmits, I suspect you are down closer to 50K PSI--and should expect brass life approximately=infinity, neck life will depend on how you perform the resizing operations. Neck sizing in 2 steps from approx 0.344 to 0.335 (Lapua) should allow you to get 20-ish reload cycles without annealing, with annealing double to tripple that.
I run weaker Winchester cases and load them up to 47.8 gr Varget* with 155 scenars leaving at 2925-2950 fps. I am currently running a non-annealing experiment usign this load. I have one set (of 50) cases that is on its 24th reload cycle without annealing.
(*) with Lapua cases you should stop near 47.5 gr which will have the same MV as 47.8 gr Varget does in Win cases. THis is from the change in case volume between L and W.
But back to the originating question: You want the headspace to be just enough that the cartrige CAN rattle around in the chamber--and by being able to do so, the case self centers and shoot accurately. Thus, you need about 0.001 radially, and about 0.001-0.002 longitudinally with 0.002-0.003 radially in the neck/throat. Any more sizing than this wears the case near the web as the case reexpands to fit the chamber durring firing and the front of the case is gripping the cham ber near the neck. The bolt is driven back (a thou or so) giving the case room to grow longitudinally. Minimizing the body sizing increases the life of the brass--and may come with a tiny amount of accuracy loss.
So, we reach a quandrary, shoot that 0.05" better and win the match, or shoot that triffling worse and have brass live a long time reducing costs. Both are good strategies--depending on the intended outcome.
Re: Regarding HEADSPACE, what is the
.
.
Re: Regarding HEADSPACE, what is the
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 308sako</div><div class="ubbcode-body">I did get to 2,940 uncorrected with the VV 140 and had awesome accuracy at which point I of course ran out of that powder lot.</div></div>
Isn't it funny how these two happen to gennerally correspond !?!
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 308sako</div><div class="ubbcode-body">I did get to 2,940 uncorrected with the VV 140 and had awesome accuracy at which point I of course ran out of that powder lot.</div></div>
Isn't it funny how these two happen to gennerally correspond !?!
